"Actual" Injector Flow #s

Here is the actual sheet RC Engineering sends after flowing your injectors.  In my case, they didn't need to be cleaned/balanced.  Excuse the poor copy quality, but I wanted to keep the file size down.



As you can see, my "720 cc/min" injectors only flow between 664 & 669 cc/min.  RC Engineering explained that this is typical and they have seen Denso "720s" flow anywhere from 660 to 740 cc/min.  The smaller injectors such as 450s and 550s will have less variance.  The fact that I'm a good 8% below what I thought I was buying is OK.  If nothing else, the smaller injectors will be easier to tune with my VPC / GCC.  I will likely also take the injectors a little past 80% IDC if I need more fuel.  I could also raise idle rail pressure from 43psi to 55psi (as an example) to get more fuel under boost (assuming I have enough adjustability with my fuel controllers to lean out idle etc.).


BTW - many people are more familiar with lbs/hr ratings, a 666.3 cc/min injector (my average) is equal to ~ 63.5 lb/hr.


RC Engineering also tested all six injectors at 95 psi with no problems (not that my pump could supply the needed flow at that high of a pressure).  I'll never see fuel rail pressures that high (idle rail pressure + boost will always be less than 95psi).


Despite a little less flow than I was expecting, I was very happy with how tight the flow population was.  RC Engineering was also surprised that all six varied by only 5 cc/min or 0.75% variance.  This is tight enough for an F1 race car (so they say)!  Even though all six are nearly identical, I'll take the higher flowing injectors and place them on the rear bank (the "hotter" cylinders).


All in all, the $10 fee per injector was well worth it for me.  Click here for more info on RC Engineering.




since August 7th, 2002


Last Updated: 08/20/02 07:00 PM